As if Sir Alex Ferguson did not have enough means of troubling opponents, he now enjoys the element of surprise. While squad rotation has long been taken for granted, the Manchester United whirl is particularly dizzying. There will surely be alterations again when the side is announced for tomorrow night's Champions League match at Bayern Munich. This perpetual revolution has been forced on the manager, but any commitment to change also suits his restless character.

So far in the Premier League, 27 players have started matches for United. The total is greater than that of the pursuing Chelsea and Arsenal. Last season, 29 individuals got into the first XI for Ferguson in the league. That marked a rise on either of the two previous campaigns in which United also took the title. The number may climb higher still.

Ferguson, for instance, seems eager to get Owen Hargreaves back in action at some stage in the next couple of months. Federico Macheda must hope eventually to be on the pitch at kick-off in this league programme. Were United fortunate enough to win the title with, say, a game to spare all sorts of players could be utilised in a dead fixture against Stoke at home on 9 May. An outing there would be a reward for someone such as Oliver Gill, a 19-year-old defender who is yet to get off the bench, but has endured a little booing because his father David stayed on as chief executive in the Glazer regime.

The manager's decisions, of course, are seldom made on compassionate grounds and the endless shuffling of the line-up was unavoidable. United, after all, have faced grave difficulties. With the dazzle of Cristiano Ronaldo gone to Real Madrid and most of the £80m fee unspent, it did seem that nobody's attention could be diverted from the seemingly shabby state of the squad.

Great veterans who remained had to bear the burden of another year. In addition to that, fitness issues meant that the centre-back partnership of Nemanja Vidic and Rio Ferdinand could be sent out only sporadically. The goalkeeper Edwin van der Sar has featured in fewer than half of United's games.

Ferguson, too, has been eking out whatever influence can still be exerted by the 35-year-old Paul Scholes. Even Ryan Giggs, whose age seldom comes to mind while his worth is so pronounced, was missing for six weeks because of a fractured arm. There has been little lamentation from the manager over any of this. Results have never been poor enough to require a recitation of the mitigating factors. Dwelling on disadvantages, too, can come perilously close to distributing excuses to the remaining members of the squad.

So far, this has been a virtuoso performance from Ferguson. The campaign started with a 1-0 victory over Birmingham at Old Trafford in which the goalkeeper Ben Foster and three of the back four could be classed as understudies. John O'Shea captained the team. Considering the context, it is almost eerie to see that United have scored eight goals more in the league than they did in the whole of last season, although Chelsea are still outgunning them. Dimitar Berbatov, who has scored a dozen goals despite looking marginalised, embodies the slightly underrated nature of United.

It is, though, the conversion of Wayne Rooney to the post of an outright centre-forward that has really stifled any maudlin reminiscing about the departure of Ronaldo, even if outsiders regret seeing a bit less of the Englishman's talent as a creative force. Rooney, absent through injury from Saturday's 4-0 win at Bolton, possesses a general robustness and has started 29 league games. Only the uncannily durable Patrice Evra has outdone him by beginning all 32 matches in the programme so far.

Rooney and Evra are around to make a reliable impact that maintains the team's overall form. The highly energetic left-back is one of the key figures in ensuring the dynamism essential to a challenge for the Premier and Champions League. The players immediately behind Evra in this season's table of appearances are Rooney, Antonio Valencia and Darren Fletcher. Valencia, with his drive and dependable crossing, has been critical to Rooney's prolific scoring. The oldest of a fairly young group is Fletcher, at 25. The Scot now has a degree of command to his work in midfield that complements the aggression.

The manager may have pulled off a trick whose effects cannot last for long, since time must track down Scholes, Giggs, Gary Neville and Van der Sar in the near future. As Bayern and others will ruefully accept, however, United continue to be a rather more potent force than onlookers could ever have anticipated.